20th level characters are just as unappealing as 1st level characters.
At level one your party is pathetic. Your sorcerer knows 6 spells, two of which are useful, your fighter can wave its sword around, and sometimes hit something. and your bard is a disappointment to the name of music.
At level 20 your sorcerer has 80+ spells/day, and is basically god, your fighter is killing the Terrasque and your bard left at level fifteen because he got funded by a wealthy patron and is now Bard Ulrich, drummer for the world renowned Bardtallica.